Liquid crystal display device

ABSTRACT

In one embodiment, a liquid crystal display device includes a first substrate and a second substrate. The first substrate includes a first gate line and a second gate line respectively extending in a first direction. A main pixel electrode is arranged between the first gate line and the second gate line and extending in a second direction orthogonally crossing the first direction. A pair of sub-common electrodes respectively faces the first gate line and the second gate line through an insulating layer and extends in the first direction. The second substrate includes a main common electrode electrically connected with the sub-common electrode and arranged on both sides sandwiching the main pixel electrode. A liquid crystal layer is held between the first substrate and the second substrate.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromprior Japanese Patent Application No. 2011-093424, filed Apr. 19, 2011,the entire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a liquid crystaldisplay device.

BACKGROUND

In recent years, a flat panel display is developed briskly, andespecially the liquid crystal display device gets a lot of attentionfrom advantages, such as light weight, thin shape, and low powerconsumption. Especially, in an active matrix type liquid crystal displaydevice equipped with a switching element in each pixel, a structureusing lateral electric field, such as IPS (In-Plane Switching) mode andFFS (Fringe Field Switching) mode, attracts attention. The liquidcrystal display device using the lateral electric field mode is equippedwith pixel electrodes and a common electrode formed in an arraysubstrate, respectively. Liquid crystal molecules are switched by thelateral electric field substantially in parallel with the principalsurface of the array substrate.

On the other hand, another technique is also proposed, in which theliquid crystal molecules are switched using the lateral electric fieldor an oblique electric field between the pixel electrode formed in thearray substrate and the common electrode formed in a counter substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate embodiments of the invention, andtogether with the general description given on and the detaileddescription of the embodiments given below, serve to explain theprinciples of the invention.

FIG. 1 is a figure schematically showing a structure of a liquid crystaldisplay device according to one embodiment.

FIG. 2 is a figure schematically showing the structure and theequivalent circuit of a liquid crystal display panel shown in FIG. 1.

FIG. 3 is a cross-sectional view schematically showing the liquidcrystal display panel including a switching element, etc.

FIG. 4 is a plan view schematically showing a structure of one pixel ina counter substrate according to a first embodiment.

FIG. 5 is a plan view schematically showing the structure of an arraysubstrate of a pixel in the liquid crystal display panel when the pixelis seen from the counter substrate side according to the firstembodiment.

FIG. 6 is a plan view showing the operation of the pixel of the liquidcrystal display panel.

FIG. 7 is a view schematically showing a cross-sectional structure ofthe liquid crystal panel taken along line A-A in FIG. 6 and an alignmentstate of liquid crystal molecules at the time of ON.

FIG. 8 is a view schematically showing a cross-sectional structure ofthe liquid crystal panel taken along line B-B in FIG. 6 and an alignmentstate of liquid crystal molecules at the time of ON.

FIG. 9 is a plan view schematically showing the structure of the arraysubstrate of the pixel according to a second embodiment when being seenfrom the counter substrate side.

FIG. 10 is a plan view schematically showing the structure of the arraysubstrate of the pixel according to a third embodiment when being seenfrom the counter substrate side.

DETAILED DESCRIPTION

A liquid crystal display device according to an exemplary embodiment ofthe present invention will now be described with reference to theaccompanying drawings wherein the same or like reference numeralsdesignate the same or corresponding parts throughout the several views.

According to one embodiment, a liquid crystal display device includes: afirst substrate including; a first gate line and a second gate linerespectively extending in a first direction, a main pixel electrodearranged between the first gate line and the second gate line andextending in a second direction orthogonally crossing the firstdirection, and a pair of sub-common electrodes respectively facing thefirst gate line and the second gate line through an insulating layer andextending in the first direction, a second substrate including a maincommon electrode electrically connected with the sub-common electrodeand arranged on both sides sandwiching the main pixel electrode; and aliquid crystal layer containing liquid crystal molecules and heldbetween the first substrate and the second substrate.

According to other embodiment, a liquid crystal display device having aplurality of pixels includes: a first substrate including; a first gateline and a second gate line respectively extending in a first direction,an auxiliary capacitance line arranged between the first gate line andthe second gate line and extending in the first direction, a firstinsulating layer covering the first gate line, the second gate line, andthe auxiliary capacitance line, a first source line and a second sourceline extending in a second direction orthogonally crossing the firstdirection on the first insulating layer, a second insulating layercovering the first and second source lines, a main pixel electrodearranged on the second insulating layer and extending in the seconddirection, the main pixel electrode being arranged between the firstgate line and the second gate line, and between the first source lineand the second source line, a pair of sub-common electrodes respectivelyfacing the first gate line and the second gate line through the secondinsulating layer and extending in the first direction, and a first maincommon electrode facing the first and second source lines through thesecond insulating layer and extending in the second direction, the firstmain common electrode being cut on the auxiliary capacitance line andelectrically connected with the sub-common electrodes, a secondsubstrate including a pair of second main common electrodes electricallyconnected with the sub-common electrodes and the first main commonelectrode, and arranged both sides sandwiching the main pixel electrode,the second main common electrodes extending in the second direction; anda liquid crystal layer containing liquid crystal molecules and heldbetween the first substrate and the second substrate.

According to other embodiment, a liquid crystal display device having aplurality of pixels includes: a first substrate including; a firstauxiliary capacitance line and a second auxiliary capacitance linerespectively extending in a first direction, a gate line arrangedbetween the first auxiliary capacitance line and the second auxiliarycapacitance line respectively extending in the first direction, a mainpixel electrode extending in a second direction orthogonally crossingthe first substrate, a sub-pixel electrode facing the gate line throughan insulating layer and extending in the first direction, the sub-pixelelectrode being electrically connected with the main pixel electrode, asecond substrate including a pair of main common electrodes arranged onboth sides sandwiching the main pixel electrode and extending in thesecond direction; and a liquid crystal layer containing liquid crystalmolecules and held between the first substrate and the second substrate.

FIG. 1 is a figure schematically showing the structure of the liquidcrystal display device 1 according to a first embodiment.

The liquid crystal display device 1 includes an active-matrix typeliquid crystal display panel LPN, a driver IC chip 2 connected to theliquid crystal display panel LPN, a flexible wiring substrate 3, abacklight 4 for illuminating the liquid crystal display panel LPN, etc.

The liquid crystal display panel LPN is equipped with an array substrateAR as a first substrate, a counter substrate CT as a second substratearranged opposing the array substrate AR, and a liquid crystal layer(not shown) held between the array substrate AR and the countersubstrates CT. The liquid crystal display panel LPN includes an activearea ACT which displays images. The active area ACT is constituted by aplurality of pixels PX arranged in the shape of a (m×n) matrix (here,“m” and “n” are positive integers).

A backlight 4 is arranged on the back side of an array substrate AR inthe illustrated example. Various types of backlights can be used as thebacklight 4. For example, a light emitting diode (LED) or a cold cathodefluorescent lamp (CCFL), etc., can be applied as a light source of thebacklight 4, and the explanation about its detailed structure isomitted.

FIG. 2 is a figure schematically showing the structure and an equivalentcircuit of the liquid crystal display panel LPN shown in FIG. 1.

The liquid crystal display panel LPN is equipped with “n” gate lines G(G1-Gn), “n” auxiliary capacitance lines C (C1-Cn), “m” source lines S(S1-Sm), etc., in the active area ACT. The gate line G and the auxiliarycapacitance line C respectively extend in a first direction X by turns.Moreover, the gate line G and the auxiliary capacitance line C arearranged in parallel each other in a second direction Y that intersectsperpendicularly the first direction X. However, they do not necessarilyextend linearly. The source lines S extend in the second direction Ythat intersects the gate line G and the auxiliary capacitance line C inparallel. Though the source lines S extend in the second direction Y,respectively, they do not necessarily extend linearly. A portion of therespective gate line G, auxiliary capacitance line C and source lines Smay be crooked partially.

Each gate line G is pulled out to the outside of the active area ACT,and is connected to a gate driver GD. Each source line S is pulled outto the outside of the active area ACT, and is connected to a sourcedriver SD. At least a portion of the gate driver GD and the sourcedriver SD is formed in the array substrate AR, for example, and the gatedriver GD and the source driver SD are connected with the driver IC chip2 provided in the array substrate AR and having an implementedcontroller.

Each pixel PX includes a switching element SW, a pixel electrode PE, acommon electrode CE, etc. Retention capacitance Cs is formed, forexample, between the auxiliary capacitance line C and the pixelelectrode PE.

In addition, in the liquid crystal display panel LPN according to thisembodiment, while the pixel electrode PE is formed in the arraysubstrate AR, the common electrode CE is formed in the array substrateAR and the counter substrate CT. Liquid crystal molecules of a liquidcrystal layer LQ are switched mainly using an electric field formedbetween the pixel electrodes PE and the common electrodes CE. Theelectric field formed between the pixel electrode PE and the commonelectrode CE is a lateral electric field substantially in parallel withthe principal surface of the array substrate AR or the principal surfaceof the counter substrate CT, or an oblique electric field slightlyoblique with respect to the principle surfaces of the substrates.

The switching element SW is constituted by n channel type thin filmtransistor (TFT), for example. The switching element SW is electricallyconnected with the gate line G and the source line S. The (m×n)switching elements SW are formed in the active area ACT.

The pixel electrode PE is electrically connected with the switchingelement SW. The (m×n) pixel electrodes PE are formed in the active areaACT. The common electrode CE is set to a common potential, for example.The common electrode CE is arranged in common to the plurality of pixelelectrodes PE through the liquid crystal layer LQ. The auxiliarycapacitance line C is electrically connected with a voltage impressingportion VCS to which the auxiliary capacitance voltage is impressed.

The array substrate AR includes an electric power supply portion VSformed outside of the active area ACT. A portion of the common electrodeCE formed on the array substrate AR is connected with the electric powersupply portion VS at the outside of the active area ACT. Furthermore, aportion of the common electrode CE formed on the counter substrate CT iselectrically connected with the electric power supply portion VS formedin the array substrate AR through an electric conductive component whichis not illustrated.

FIG. 3 is a cross-sectional view schematically showing the liquidcrystal display panel LPN containing the switching element SW. Here,illustration of a common electrode is omitted and only the part requiredfor explanation is illustrated.

The backlight 4 is arranged at the back side of the array substrate ARwhich constitutes the liquid crystal display panel LPN.

The array substrate AR is formed using an insulating substrate 10 havinga light transmissive characteristic, such as a glass substrate and aplastic substrate. This array substrate AR includes the switchingelement SW, the pixel electrode PE, a first alignment film AL1, etc., onthe side facing the counter substrate CT of the first insulatingsubstrate 10.

In the example shown here, the switching element SW may be either atop-gate-type switching element or a bottom-gate-type switching element,and includes a semiconductor layer formed of poly-silicon or amorphoussilicon, though the detailed description thereof is not made.

The semiconductor layer SC has a source region SCS and a drain regionSCD on both sides which face across a channel region SCC, respectively.In addition, an undercoat layer which is an insulating film may bearranged between the first insulating substrate 10 and the semiconductorlayer SC. The semiconductor layer SC is covered with a gate insulatingfilm 11. Moreover, the gate insulating film 11 is arranged also on thefirst insulating substrate 10.

The gate electrode WG is formed on the gate insulating film 11, and islocated on the channel region SCC of the semiconductor layer SC. Thegate line G and the auxiliary capacitance line C are also formed on thegate insulating film 11. The gate electrode WG, the gate line G and theauxiliary capacitance line C may be formed using the same material andthe same process. The gate electrode WG is electrically connected withthe gate line G.

The gate electrode WG of the switching element SW, the gate line G andthe auxiliary capacitance line C are covered with a first interlayerinsulating film 12. Moreover, the first interlayer insulating film 12 isarranged also on the gate insulating film 11. The gate insulating layer11 and the first interlayer insulating film 12 are formed of aninorganic system material, such as silicon oxide and a silicon nitride.

A source electrode WS and a drain electrode WD of the switching elementSW are formed on the first interlayer insulating film 12. The sourceline (not shown) is also formed on the first interlayer insulating film12. The source electrode WS, the drain electrode WD, and the sourcelines may be formed using the same process and the same material. Thesource electrode WS is electrically connected with the source line.

The source electrode WS is in contact with the source region SCS of thesemiconductor layer SC through a contact hole which penetrates the gateinsulating film 11 and the first interlayer insulating film 12. Thedrain electrode WD is in contact with the drain region SCD of thesemiconductor layer SC through a contact hole which penetrates the gateinsulating film 11 and the first interlayer insulating film 12. The gateelectrode WG, the source electrode WS, and the drain electrode WD areformed of electric conductive materials, such as molybdenum, aluminum,tungsten, and titanium, for example.

The switching element SW as described-above is covered with a secondinterlayer insulating film 13. That is, the source electrode WS, thedrain electrode WD, and the source lines are covered with the secondinterlayer insulating film 13. Moreover, the second interlayerinsulating film 13 is arranged also on the first interlayer insulatingfilm 12. This second interlayer insulating film 13 is formed of variousorganic materials, such as ultraviolet curing type resin and heat curingtype resin, for example.

The pixel electrode PE is formed on the second interlayer insulatingfilm 13. The pixel electrode PE is connected with the drain electrode WDthrough a contact hole which penetrates the second interlayer insulatingfilm 13. Though pixel electrode PE is formed by light transmissiveconductive materials, such as Indium Tin Oxide (ITO), Indium Zinc Oxide(IZO), etc, other metals such as aluminum may be used.

In addition, the array substrate AR is further equipped with asub-common electrode as a portion of the common electrode to bementioned later. Furthermore, a main common electrode may be equipped.

The first alignment film AL1 is arranged on a surface of the arraysubstrate AR facing the counter substrate CT, and extends approximatelywhole region of the active area ACT. The first alignment film AL1 coversthe pixel electrode PE, and is also formed on the second interlayerinsulating film 13. The first alignment film AL1 is formed of thematerial which shows a lateral alignment characteristics.

On the other hand, the counter substrate CT is formed using a secondtransmissive insulating substrate 20, such as a glass substrate and aplastic substrate. The counter substrate CT includes a second maincommon electrode of the common electrodes and the second alignment filmAL2 on the surface of the second insulating substrate 20 facing thearray substrate AR. A black matrix arranged facing wiring portions suchas the source line S, the gate line G, the auxiliary capacitance line C,and the switching element SW to define the respective pixels PX, colorfilter layers arranged corresponding to the pixels PX, and an overcoatlayer to smooth the concave and depression of the surface of the blackmatrix and the color filter layer may be formed on the counter substrateCT.

The common electrode is formed of the electric conductive material whichhas light transmissive characteristics, such as ITO and IZO, forexample.

The second alignment films AL2 is arranged on a surface of the countersubstrate CT opposing the surface of the array substrate AR, and extendsapproximately whole of the active area ACT. The second alignment filmsAL2 covers the second main common electrode of the common electrodes(not shown) and the like. The second alignment films AL2 is formedmaterials which have a lateral alignment characteristics

An alignment processing (for example, rubbing processing and photoalignment processing) is performed for making the first and secondalignment films AL1 and AL2 in an initial alignment state. The directionof the first alignment processing where the first alignment AL1 carriesout the initial alignment of the liquid crystal molecule, and thedirection of the second alignment processing where the second alignmentAL2 carries out the initial alignment of the liquid crystal molecule,are respectively directions in parallel to the second direction Y. Thefirst and second alignment directions are in parallel and in the samedirections or reverse directions each other.

The array substrate AR and the counter substrate CT as mentioned-aboveare arranged so that the first alignment film AL1 and the secondalignment film AL2 face each other. In this case, the pillar-shapedspacer is formed integrally with one of the substrates by resin materialbetween the first alignment film AL1 on the array substrate AR and thesecond alignment film AL2 on the counter substrate CT. Thereby, apredetermined gap, for example, a 3-7 μm cell gap, is formed, forexample. The array substrate AR and the counter substrate CT are pastedtogether by the seal material which is not illustrated, in which thepredetermined cell gap is formed.

The liquid crystal layer LQ is held at the cell gap formed between thearray substrate AR and the counter substrate CT, and is arranged betweenthe first alignment film AL1 and the second alignment film AL2. Theliquid crystal layer LQ contains the liquid crystal molecule which isnot illustrated. The liquid crystal layer LQ is constituted by positivetype liquid crystal material.

A first optical element OD1 is attached to the external surface of thearray substrate AR, i.e., the external surface of the first insulatingsubstrate 10 which constitutes the array substrate AR by adhesives, etc.The first optical element OD1 contains first polarizing plate PL1 whichhas a first polarization axis. Moreover, a second optical element OD2 isattached to the external surface of the counter substrate CT, i.e., theexternal surface of the second insulating substrate 20 which constitutesthe counter substrate CT by adhesives, etc. The second optical elementOD2 contains a second polarizing plate PL2 which has a secondpolarization axis. The first polarization axis of the first polarizingplate PL1 and the second polarization axis of the second polarizingplate PL2 has a relationship in which both axis intersectperpendicularly, for example. One polarizing plate is arranged, forexample, so that its polarizing direction is the direction of the longaxis of the liquid crystal molecule, i.e., the first alignmentprocessing direction or a parallel direction to the second alignmentprocessing direction (or in parallel to the second direction Y), or inorthogonal direction (or in parallel to the first direction X). Thereby,the normally black mode is achieved.

Hereinafter, one example of the structure of the embodiment is explainedmore practically.

First Embodiment

FIG. 4 is a plan view schematically showing the structure of one pixelin the counter substrate constituting the liquid crystal display panelLPN according to a first embodiment.

The common electrode CE has a sub-common electrode extending along thefirst direction X and a main common electrode extending along the seconddirection Y. In this embodiment, the counter substrate CT is equippedwith a second main common electrode CA2 as the common electrode CE, anda sub-common electrode CB1 on the array substrate to be mentioned lateras the sub-common electrode.

That is, the illustrated counter substrate CT is equipped with thebelt-like second main common electrode CA2 extending linearly along thesecond direction Y. In the illustrated example, the common electrode CEis formed in the counter substrate CT in the shape of a stripe extendingin the second direction Y. Moreover, the illustrated second main commonelectrode CA2 is located in two lines 2 in parallel along the firstdirection X. Hereinafter, in order to distinguish the second main commonelectrodes CA2, the second main common electrode CA2 of the left-handside in the figure is called CAL2, and the second main common electrodeCAL2 of the right-hand side in the figure is called CAR2. In addition,the counter substrate CT may be equipped with a sub-common electrode.

The second main common electrodes CA2 of the common electrode CE in theactive area are pulled out to the outside of the active area, and iselectrically connected with the electric supply portion formed on thearray substrate AR through a conductive element, respectively. Thereby,electric power of common potential is supplied to the second main commonelectrode CA2.

FIG. 5 is a plan view schematically showing the structure of the arraysubstrate AR when one pixel PX of the liquid crystal panel LPN accordingto the first embodiment is seen from the counter substrate CT side. Inaddition, only structure required for the explanation in one PX isillustrated, and illustration of the switching element, etc., isomitted.

The array substrate AR includes gate lines G1 and G2 extending along thefirst direction X, an auxiliary capacitance line C1 extending along thefirst direction X, a source line S1 and a source line S2 extending alongthe second direction Y, a pixel electrode PE, and a belt-like sub-commonelectrode CB1 extending linearly along the first direction X as aportion of the common electrodes CE. The auxiliary capacitance line C1,the gate line G1, and the gate line G2 are formed on the gate insulatingfilm 11, and are covered with the first interlayer insulating film 12.The source line S1 and the source line S2 are formed on the firstinterlayer insulating film 12, and are covered with the secondinterlayer insulating film 13. The pixel electrode PE is formed on thesecond interlayer insulating film 13. The sub-common electrode CB1 isformed on the second interlayer insulating film 13, for example, likethe pixel electrode PE.

In the illustrated example, the pixel PX corresponds to a region shownin a dashed line in the figure, and has the shape of a rectangle inwhich the length in the second direction Y is longer than that in thefirst direction X. Moreover, in the illustrated example, the source lineS1 is arranged at the left-hand side end in the pixel PX. Precisely, thesource line S1 is arranged striding over a boundary between theillustrated pixel and the pixel which adjoins the illustrated pixel PXat its left-hand side end. The source line S2 is arranged at theright-hand side end. Precisely, the source line S2 is also arrangedstriding over a boundary between the illustrated pixel and the pixelwhich adjoins the illustrated pixel PX at its right-hand side end. Theauxiliary capacitance line C1 is arranged approximately in the centralportion of the pixel PX. In addition, the gate line G1 is arrangedstriding over a boundary between the illustrated pixel PX and anadjacent pixel PX on the upper side. Similarly, the gate line G2 isarranged striding over a boundary between the illustrated pixel PX andan adjacent pixel on the bottom side.

In the common electrode CE, when the sub-common electrode CB1 is formedon the second interlayer insulating film 13 with the pixel electrode PE,the sub-common electrode CB1 can be formed using the same process andthe same materials (for example, ITO, etc.) as the pixel electrode PE.In this case, the sub-common electrode CB1 is electrically insulatedfrom the pixel electrode PE and is apart from the pixel electrode PE.The sub-common electrode CB1 and the pixel electrode PE may be formed indifferent layers each other by interposing other interlayer insulatinglayer between the sub-common electrode CB1 and the pixel electrode PE.In this case, the sub-common electrode CB1 may be formed of materialwhich is different from the pixel electrode PE or same material as thepixel electrode PE.

The sub-common electrodes CB1 linearly extends in each active area andare pulled out to the outside of the active area, and further iselectrically connected with the electric supply portion formed on thearray substrate AR, respectively. Thereby, electric power of commonpotential is supplied to the sub-common electrode CB1. That is, thesub-common electrode CB1 and the second main common electrode CA2 areelectrically connected each other.

In the illustrated example, a pair of sub-common electrodes CB1 isarranged in the first direction X in parallel each other. Hereinafter,in order to distinguish the sub-common electrodes CB1, the sub-commonelectrode CB1 on the upper side is called a sub-common electrode CBU1,and the sub-common electrode CB1 on the lower side is called asub-common electrode CBB1. The sub-common electrodes CBU1 is arranged onthe upper side facing the gate line G1. That is, the sub-commonelectrode CBU1 is arranged striding a boundary between the illustratedpixel and an adjoining pixel on the upper side. The sub-commonelectrodes CBB1 is arranged on the lower side facing the gate line G2.That is, the sub-common electrode CBB1 is arranged striding a boundarybetween the illustrated pixel and an adjoining pixel on the lower side.The first interlayer insulating film 12 and the second interlayerinsulating film 13 are respectively interposed between the sub-commonelectrode CBU1 and the gate line G1, and between the sub-commonelectrode CBB1 and the gate line G2

In case the respective sub-common electrodes CBU1 and CBB1 cover thegate line G1 and the gate line G2 in the active area, that is, thesub-common electrode CBU1 is arranged on the gate line G1 and thesub-common electrode CBB1 is arranged on the gate line G2, the widths ofthe respective sub-common electrodes CBU1 and CBB1 along the seconddirection Y are substantially equal to or more than those of the gateline G1 and the gate line G2.

Moreover, in the illustrated example, as shown in a dashed line, thesecond main common electrode CAL2 formed in the counter substrate CT andconstituting the common electrode CE is arranged at the left-hand sideend of pixel PX, and faces the source line S1. That is, the second maincommon electrode CAL2 is arranged striding over a boundary between theillustrated pixel and an adjoining pixel on its left-hand side.Similarly, the second main common electrode CAR2 is arranged at theright-hand side end of the pixel PX, and faces the source line S2. Thatis, the second main common electrode CAR2 is arranged striding over aboundary between the illustrated pixel and an adjoining pixel on itsright-hand side.

The pixel electrode PE is arranged between the source line S1 and thesource line S2. In addition, the pixel electrode PE is arranged betweenthe gate line G1 and the gate line G2 i.e., between the sub-commonelectrode CBU1 and the sub-common electrode CBB1. The pixel electrode PEis electrically connected with the switching element which is notillustrated. The pixel electrode PE has a belt-like main pixel electrodePA extending linearly along the second direction Y, and a belt-likecapacitance portion PC extending linearly along the first direction X.The main pixel electrodes PA and the capacitance portion PC areelectrically connected. In the illustrated example, the main pixelelectrode PA and capacitance portion PC are integrally or continuouslyformed. That is, in the array substrate AR, the pixel electrode PE isformed in the shape of an approximately cross.

The main pixel electrode PA is arranged in an inside position of thepixel PX rather than the position right on the adjoining source line S1and the source line S2, and is arranged between the source line S1 andthe source line S2. More specifically, the main pixel electrode PA isarranged in the approximately center position between the source line S1and the source line S2. The main pixel electrode PA extends from nearthe upper end to near a bottom end of the pixel PX.

In the illustrated example, the capacitance portion PC is arranged onthe auxiliary capacitance line C1. Between the capacitance portion PCand the auxiliary capacitance line C1, a first interlayer insulatingfilm 12 and a second interlayer insulating film 13 are interposed asinsulating films. That is, the capacitance portion PC is arranged in aninside position of the pixel PX rather than the position right on theadjoining gate line G1 and the gate line G2, and is arranged between thegate line G1 and the gate line G2 or between the sub-common electrodeCBU1 and the sub-common electrode CBB1. More practically, thecapacitance portion PC is arranged approximately in the center of thepixel between the gate line G1 and the gate line G2. The capacitanceportion PC intersects the main pixel electrode PA, and linearly extendsfrom the main pixel electrode PA toward its both sides, i.e., toward thesource line S1 on the left-hand side, and the source line S2 of theright-hand side of the main pixel electrode PA, respectively.

According to this embodiment, the second main common electrode CAL2 isarranged at the both sides which sandwich the main pixel electrode PA.In other word, the main pixel electrode PA and the second main commonelectrode CAL2 are arranged in the first direction X in turns. The mainpixel electrode PA and the second main common electrode CA2 are arrangedapproximately in parallel each other. In this case, neither of thesecond main common electrodes CA2 overlaps with the main pixel electrodePA in a X-Y plane.

That is, one main pixel electrode PA is located between the adjoiningsecond main common electrode CAL2 and the adjoining second main commonelectrode CAR2. The second main common electrode CAL2 and the secondmain common electrode CAR2 are arranged at the both sides which faceacross the position above the main pixel electrode PA. That is, the mainpixel electrode PA is arranged between the second main common electrodeCAL2 and the second main common electrode CAR2. Accordingly, the secondmain common electrode CAL2, the main pixel electrode PA, and the secondmain common electrode CAR2, are arranged along the first direction X inthis order. The distance between the second main common electrode CAL2and the main pixel electrode PA is approximately the same as thatbetween the second main common electrode CAR2 and the main pixelelectrode PA in the first direction X.

The sub-common electrode CB1 is arranged on the both sides whichsandwich the capacitance portion PC. That is, the sub-common electrodeCB1 and the capacitance portion PC are arranged by turns along thesecond direction Y. The sub-common electrode CB1 and the capacitanceportion PC are arranged approximately in parallel each other. In thiscase, neither of the sub-common electrodes CB1 overlaps the capacitanceportion C in the X-Y plane.

Namely, one capacitance portion PC is located between the sub-commonelectrodes CBU1 and the sub-common electrodes CBB1. The sub-commonelectrodes CBU1 and the sub-common electrode CBB1 are arranged on theboth sides which sandwich the capacitance portion PC, i.e., thecapacitance portion PC is arranged between the sub-common electrode CBU1and the sub-common electrode CBB1. The sub-common electrode CBU1, thecapacitance portion PC, and the sub-common electrode CBB1 are arrangedalong the second direction Y in this order.

FIG. 6 is a plan view showing one pixel showing an operation of theliquid crystal display panel.

At the time of non-electric field state, i.e., when a potentialdifference (i.e., electric field) is not formed between the pixelelectrode PE and the counter electrode CE, the liquid crystal moleculesof the liquid crystal layer LQ are aligned so that their long axis arealigned in a parallel direction with a first alignment processingdirection of the first alignment film AL1 and a second alignmentprocessing direction of the second alignment film AL2. In this state, atthe time of OFF, the alignment state corresponds to the initialalignment state, and the alignment direction of the liquid crystalmolecule corresponds to the initial alignment direction.

In addition, precisely, the liquid crystal molecules LM are notexclusively aligned in parallel with the X-Y plane, but are pre-tiltedin many cases. For this reason, the precise direction of the initialalignment is a direction in which an orthogonal projection of thealignment direction of the liquid crystal molecule LM is carried out tothe X-Y plane at the time of OFF. However, in order to explain simplyhereinafter, the liquid crystal molecule LM is assumed that the liquidcrystal molecule LM is aligned in parallel with the X-Y plane, and isexplained as what rotates in a field in parallel to the X-Y plane.

Here, the first alignment processing direction of the first alignmentfilm AL1 and the second alignment processing direction of the secondalignment film AL2 are directions in parallel to the second direction Y,respectively. At the time of OFF, the long axis of the liquid crystalmolecule LM is aligned substantially in parallel to the second directionY as shown in a dashed line in the figure. That is, the direction ofinitial alignment of the liquid crystal molecule LM is in parallel tothe second direction Y.

In addition, when both the first alignment processing direction of thefirst alignment film AL1 and the second alignment processing directionof the second alignment film AL2 are in parallel, and are reversedirections each other, the liquid crystal molecule LM is aligned so thatthe liquid crystal molecule LM is aligned with an approximately uniformpre-tilt angle near the first and second alignment films AL1 and AL2 andin the intermediate portion of the liquid crystal layer LQ (homogeneousalignment) in a cross-section of the liquid crystal layer LQ. Inaddition, when the respective directions of the alignment processing forthe first alignment film AL1 and the second alignment film AL2 are inparallel and the same directions each other, the liquid crystal moleculeLM is aligned with approximately horizontal direction (i.e., thepre-tilt angle is approximately zero). The liquid crystal molecule LM isaligned with the pre-tilt angle so that the alignment of the liquidcrystal molecule LM near the first alignment film AL1 and the secondalignment film AL2 becomes symmetrical with respect to the intermediateportion of the liquid crystal layer LQ (splay alignment).

Some of the back light from the backlight 4 enters into the liquidcrystal display panel LPN after penetrating the first polarizing platePL1. The polarization state of the light which enters into the liquidcrystal display panel LPN changes depending on the alignment state ofthe liquid crystal molecule LM when the light passes the liquid crystallayer LQ. At the time of OFF, the light which passes the liquid crystallayer LQ is absorbed by the second polarizing plate PL2 (black display).

On the other hand, in case where the potential difference is formedbetween the pixel electrode PE and the common electrode CE (at the timeof ON), the lateral electric field in parallel to the substrate (oroblique electric field) is formed between the pixel electrode PE and thecommon electrode CE. Thereby, the liquid crystal molecule LM rotates ina parallel plane with the substrate surface so that the long axisbecomes in parallel with the direction of the electric field as shown ina solid line in the figure.

In the example shown in the figure, the pixel is divided into fourdomains (apertures) by the main pixel electrode PA and the capacitanceportion PC. That is, the liquid crystal molecule LM surrounded by themain pixel electrode PA, the sub-common electrode CBU1 and the secondmain common electrode CAL2 rotates counterclockwise with respect to thesecond direction Y along with the lateral electric field, and issubstantially aligned so that the liquid crystal molecule LM may turn tothe upper left direction in the figure. The liquid crystal molecule LMsurrounded by the main pixel electrode PA, the sub-common electrode CBU1and second main common electrode CAR2 rotates clockwise with respect tothe second direction Y along with the lateral electric field, and issubstantially aligned so that the liquid crystal molecule LM may turn tothe upper right direction in the figure. The liquid crystal molecule LMsurrounded by the main pixel electrode PA, the sub-common electrode CBB1and the second main common electrode CAL2 rotates clockwise with respectto the second direction Y along with the lateral electric field, and issubstantially aligned so that the liquid crystal molecule LM may turn tothe lower left direction in the figure. The liquid crystal molecule LMsurrounded by the main pixel electrode PA, the sub-common electrode CBB1and the second main common electrode CAR2 rotates counterclockwise withrespect to the second direction Y along with the lateral electric field,and is substantially aligned so that the liquid crystal molecule LM mayturn to the lower right direction in the figure.

Thus, in each pixel PX, in the state where the horizontal electric fieldis formed between the pixel electrode PE and the common electrode CE,the alignment direction of the liquid crystal molecule LM is dividedinto at least four groups of directions, and four domains are formedcorresponding respective alignment directions. That is, at least fourdomains are formed in each pixel PX.

At the time of ON, the light which entered into the liquid crystal panelLPN from the backlight 4 enters into the liquid crystal layer LQ. Whenthe back light which entered into the liquid crystal layer LQ passesthrough four domains (apertures) divided by the pixel electrode PE andthe common electrode CE, respectively, the polarization state changes.At the time of ON, at least a portion of light which passed the liquidcrystal layer LQ penetrates the second polarizing plate PL2 (whitedisplay).

FIG. 7 is a view schematically showing a cross-sectional structure ofthe pixel taken along line A-A shown in FIG. 6 and an alignment state ofthe liquid crystal molecules at the time of ON.

In this embodiment, the alignment of the liquid crystal molecule LM iscontrolled by electric field mainly formed of the potential differencebetween the main pixel electrode PA and the second main common electrodeCA2. On the both sides of the main pixel electrode PA, the liquidcrystal molecule LM on the left-hand side domain is aligned by electricfield between the main pixel electrode PA and the second main commonelectrode CAL2 so that the molecule LM may approximately turn on theleft-hand side in the figure. The liquid crystal molecule LM in theright-hand side domain is aligned by electric field between the mainpixel electrode PA and the second main common electrode CAR2 so that themolecule LM may approximately turn on the right-hand side in the figure.

FIG. 8 is a view schematically showing a cross-sectional structure ofthe pixel taken along line B-B shown in FIG. 6 and an alignment state ofthe liquid crystal molecules at the time of ON.

In this embodiment, the liquid crystal molecule LM is aligned by theelectric field mainly between the capacitance portion PC and thesub-common electrode CB1. However, the alignment of the liquid crystalmolecule LM is controlled by a mutually affected electric field formedbetween the main pixel electrode PA and the sub-common electrode CB1 andbetween the capacitance portion PC and the second main common electrodeCA2 other than between the main pixel electrode PA and the second maincommon electrode CA2. In the pixel divided into upper portion and lowerportion by the capacitance portion C, the liquid crystal molecule LM inthe upper portion is aligned so as to direct on the substantially upperside by the electric field between the capacitance portion PC and thesub-common electrode CBU1. The liquid crystal molecule LM in the lowerside portion is aligned so as to direct on the substantially lower sidein the figure by the electric field between the capacitance portion PCand the sub-common electrode CBB1.

According to this embodiment, it becomes possible to form at least fourdomains in one pixel. Therefore, the viewing angle in at least fourdirections can be compensated optically, and a wide viewing angle isattained. Accordingly, it becomes possible to offer a high qualitydisplay device.

Moreover, the transmissivity of each domain becomes equal by setting upthe area of at least four apertures divided by the pixel electrode PEand the common electrode CE substantially equal in one pixel. Therefore,it becomes possible to achieve a uniform display with wide viewing angleby compensating the light passing the respective apertures each other.

Furthermore, since the sub-common electrode CB1 is arranged so that thesub-common electrode CB1 counters with the gate line, it becomespossible to shield undesired electric field from the gate line. For thisreason, it becomes possible to suppress that undesirable bias isimpressed from the gate line to the liquid crystal layer LQ, thatdisplay defect such as a printed picture is generated, and further thatlight leak is generated due to the disorder of the alignment of theliquid crystal molecule. Therefore, a high quality liquid crystaldisplay device can be offered.

Since the regions between the main pixel electrode PA and the sub-commonelectrode CB1, and between the capacitance portion PC and the secondmain common electrode CA2 become apertures to contribute the display,the regions can contribute to the transmissivity.

The shield performance against the electric field from the gate line isimproved with the increase of the width of the sub-common electrode CB1.However, since the aperture which contributes to the display is alsoformed between the sub-common electrode CB1 and the main pixel electrodePE, if the width of the sub-common electrode CB1 is too wide, the areaof the aperture becomes small, and reduction of transmissivity iscaused. Therefore, it becomes possible to raise the electric fieldshield performance against the electric field from the gate lines whilemaintaining high transmissivity in the case where the sub-commonelectrode CBU1 and the sub-common electrode CBB1 are respectivelyarranged on the gate line G1 and the gate line G2, and havesubstantially the same widths as the gate line G1 and the gate line G2.

In this embodiment, the second main common electrode CAL2 and the secondcommon electrode CAR2 counter with the source line S1 and the sourceline S2, respectively. When the second main common electrode CAL2 andthe second main common electrode CAR2 are especially arranged above thesource line S1 and the source line S2, respectively, the aperture whichcontributes to the display can be expanded as compared with the casewhere the second main common electrode CAL2 and the second main commonelectrode CAR2 are arranged on the main pixel electrode PA side ratherthan on the source line S1 and the source line S2, and it becomespossible to improve the transmissivity of the pixel PX.

Moreover, it becomes possible to expand the distances between the mainpixel electrode PA and the second main common electrode CAL2, andbetween the main pixel electrode PA and the second main common electrodeCAR2 by arranging each of the second main common electrodes CAL2 and thesecond main common electrode CAR2 above the source line S1 and thesource line S2, respectively, and also becomes possible to form morehorizontal electric field closer to the horizontal direction. For thisreason, it becomes possible to also maintain the wide viewing anglewhich is advantages of the general IPS mode.

Furthermore, at the time of ON, since horizontal electric field ishardly formed (or sufficient electric field to drive the liquid crystalmolecule LM is not formed), the liquid crystal molecule LM hardly movesfrom the initial alignment direction like at the time of OFF. For thisreason, as mentioned-above, even if the pixel electrode PE and thecommon electrode CE are formed of the electric conductive material withthe light transmissive characteristics in these domains, back lighthardly penetrates, and hardly contributes to the display at the time ofON. Therefore, the pixel electrode PE and the common electrode CE do notnecessarily need to be formed of a transparent electric conductivematerial, and may be formed using electric conductive materials, such asaluminum and silver.

Moreover, when an assembling shift occurs between the array substrate ARand the counter substrate CT, a difference may arises in distancesbetween the respective common electrodes CE of the both sides and thepixel electrode PE. However, the alignment shift is produced in commonto all the pixels PX, there is no difference in the electric fielddistribution between the pixels PX, and the influence to the display ofthe image is negligible.

Second Embodiment

FIG. 9 is a plan view schematically showing the structure of the arraysubstrate of one pixel according to a second embodiment when being seenfrom the counter substrate CT side. In addition, only the structure ofone pixel PX required for the explanation is illustrated, and theillustration of the switching element, etc., is omitted. Moreover, adashed line shows the second main common electrode CA2 of the countersubstrate which is not illustrated in the figure.

In this second embodiment, the counter substrate CT of the firstembodiment shown in FIG. 4 is applicable. The common electrode CEincludes a first main common electrode CA1 formed on the array substrateAR and the second main common electrode CA2 formed on the countersubstrate CT as a main common electrode, and a sub-common electrode CB1formed on the array substrate AR.

The array substrate AR includes the gate line G1 and the gate line G2,the auxiliary capacitance line C1, the source line S1 and the sourceline S2, and the pixel electrode PE like the first embodiment. Moreover,the array substrate AR includes the sub-common electrode CB1 linearlyextending along the first direction X as the common electrode CE in abelt-like shape and the first main common electrode CA1 extendinglinearly along the second direction Y in the belt-like shape. Thesub-common electrode CB1 and the first main common electrode CA1 areformed on the second interlayer insulating film 13, for example, likethe pixel electrode.

In the common electrode CE, when the sub-common electrode CB1 and thefirst main common electrode CA1 are formed on the second interlayerinsulating film 13 with the pixel electrode PE, the sub-common electrodeCB1 and the first main common electrode CA1 can be formed by the sameprocess using the same materials (for example, ITO, etc.) as the pixelelectrode PE. In this case, the sub-common electrode CB1 and the firstmain common electrode CA1 are insulated electrically from the pixelelectrode PE, and are apart from the pixel electrode PE, respectively.In addition, other interlayer insulating film may be interposed betweenthe sub-common electrode CB1 and the first main common electrode CA1,and the pixel electrode layer PE. Thereby, the sub-common electrode CB1and the first main common electrode CA1 may be formed in a differentlayer from the pixel electrode PE. In this case, the sub-commonelectrode CB1 and the first main common electrode CA1 are formed bydifferent material from the pixel electrode PE or may be formed of thesame material as the pixel electrode PE.

The sub-common electrode CB1 (the illustrated sub-common electrode CBU1and the sub-common electrode CBB1) linearly extends facing the gate linein the active area like the first embodiment, respectively. Moreover,the sub-common electrode CB1 is pulled out to the outside of the activearea, and electrically connected with the electric supply portion formedin the array substrate AR, and electric power of common potential issupplied to the sub-common electrode CB1. That is, the sub-commonelectrode CB1 and the second main common electrode CA2 are electricallyconnected.

Moreover, the first main common electrode CA1 extends linearly, facingthe source lines in the active area, respectively. However, the firstmain common electrode CA1 is cut off on the auxiliary capacitance lineC1. The first main common electrode CA1 is electrically connected withthe sub-common electrode CB1. In the illustrated example, the first maincommon electrode CA1 and the sub-common electrode CB1 are formedintegrally and continuously. Moreover, in the illustrated example, thefirst main common electrode CA1 is located in two lines in parallel eachother along the first direction X. Hereinafter, in order to distinguishthe first main common electrodes CA1, the first main common electrodeCA1 on the left-hand side in the figure is called CAL1, and the firstmain common electrode on the right-hand side in the figure is calledCAR1.

The first main common electrode CAL1 is arranged at the left-hand sideend of the pixel PX, and faces the source line S1. That is, the firstmain common electrode CAL1 is arranged striding over a boundary betweenthe illustrated pixel and a pixel adjoining the illustrated pixel PX onits left-hand side. However, the first main common electrode CAL1 is notarranged on an intersection portion with the source line S1 whichintersects the auxiliary capacitance line C1.

The first main common electrode CAR1 is arranged at the right-hand sideend of the pixel PX, and faces the source line S2. That is, the firstmain common electrode CAR1 is arranged striding over a boundary betweenthe illustrated pixel and an adjoining pixel PX on its right-hand side.However, the first main common electrode CAR1 is not arranged on anintersection portion with the source line S2 which intersects theauxiliary capacitance line C1.

The second interlayer insulating film 13 is interposed, respectivelybetween the first main common electrode CAL1 and the source line S1 andbetween the first main common electrode CAR1 and the source line S2.

In case the first main common electrode CAL1 and the first main commonelectrode CAR1 cover the source line S1 and the source line S2 in theactive area, respectively, that is, the first main common electrode CAL1is arranged on the source line S1, and similarly when the first maincommon electrode CAR1 is arranged on the source line S2, the respectivewidths of the first main common electrodes CAL1 and CAR1 in the firstdirection X are equal to or larger than those of the source line S1 andthe source line S2 in the first direction X.

In the illustrated example, the second main common electrode CAL2 formedon the counter substrate CT and constituting the common electrode CE isarranged at the left-hand side end of the pixel PX, and faces the firstmain common electrode CAL1. Similarly, the second main common electrodeCAR2 formed on the counter substrate CT and constituting the commonelectrode CE is arranged at the right-hand side end of the pixel PX, andfaces the first main common electrode CAR1. Off course, the second maincommon electrode CAL2 and the second main common electrode CAR2 extendin the second direction without being cut above the auxiliarycapacitance line C1.

According to the second embodiment, the same effect as the firstembodiment is achieved. It is possible to suppress the application ofundesirable bias from the source line to the liquid crystal layer LQ byshielding undesirable electric field from the source line because thefirst main common electrode CA1 of the common electrode CE is arrangedso as to face the source line. Thereby the generation of a defectdisplay such as a cross talk is controlled. Namely, in the state where apixel PX is set to a potential to display the black image, thephenomenon of rising up of luminosity resulted from light leak of thepixel is suppressed when the pixel potential which displays white issupplied to the source line connected to the pixel PX. Thereby, itbecomes possible to control the generating of a poor display.Accordingly, a higher quality liquid crystal display device can beoffered.

The shield performance against electric field from the source line isimproved with the increase of the width of the first main commonelectrode CA1. However, since the aperture which mainly contributes tothe display is formed between the first main common electrode CA1 andthe main pixel electrode PA, if the width of the first main commonelectrode CA1 is too wide, the area of the aperture becomes small andreduction of transmissivity is caused. Therefore, it becomes possible toraise the electric field shield performance against the electric fieldfrom the source lines while maintaining high transmissivity in the casewhere the first main common electrode CAL1 and the first main commonelectrode CAR1 are respectively arranged on the source line S1 and thesource line S2, and have substantially the same widths as those of thesource line S1 and the source line S2.

Moreover, in this second embodiment, it becomes possible to control ashort-circuit of the pixel electrode PE with the common electrode CE,even if the first main common electrode CA1 is formed on the same layeras the pixel electrode PE, because the capacitance portion PC facing theauxiliary capacitance line C1 is apart from the first main commonelectrode CA1 cut off on the auxiliary capacitance line C1.

In addition, the auxiliary capacitance line is arranged in the centralportion of the pixel in the first and second embodiments. Theembodiments are especially suitable for a capacitance coupling dotinversion driving (CCDI driving) in which a capacitance coupling drivingis performed using a dot inversion driving. That is, the pixel voltageis reached to a predetermined voltage by superimposing an auxiliarycapacitance signal on the pixel electrode PE through a retentioncapacitance Cs of each pixel in the capacitance coupling driving (CCdriving). Thereby, signal voltage amplitude can be approximately reducedby half if the retention capacitance Cs and the pixel capacitance areset to be equal. In the CCDI driving, the retention capacitance Cs ofthe adjacent pixels PX is coupled to mutually different auxiliarycapacitance lines C, respectively, and the auxiliary capacitancevoltages supplied to the retention capacitance Cs of the adjacent pixelsPX are made mutually different polarities. The driver IC chip 2including the gate driver GD, the source driver SD, and the controllerfunctions as driving means for performing the CCDI driving, and isequipped in the array substrate AR.

According to the structure using the CCDI driving, while being able toreduce power consumption, it becomes possible to control the degradationof display grace.

Third Embodiment

FIG. 10 is a plan view schematically showing the structure of the arraysubstrate of one pixel according to a third embodiment when being seenfrom a counter substrate CT side. In addition, only the structure of onepixel PX required for the explanation is illustrated, and theillustration of the switching element, etc., is omitted. Moreover, adashed line shows the second main common electrode CA2 of the countersubstrate which is not illustrated in the figure.

In this third embodiment, the counter substrate CT of the firstembodiment shown in FIG. 4 is applicable. The common electrode CEincludes the second main common electrode CA2 formed on the countersubstrate CT as the main common electrode.

The array substrate AR includes an auxiliary capacitance line C1 and anauxiliary capacitance line C2 extending in the first direction X, a gateline G1 arranged between the auxiliary capacitance line C1 and theauxiliary capacitance line C2 and extending in the first direction X, asource line S1 and a source line S2 extending in the second direction Y,and a pixel electrode PE extending in the first direction X.

In the illustrated example, the source line S1 is arranged at theleft-hand side end in the pixel PX. Precisely, the source line S1 isarranged striding over a boundary between the illustrated pixel and apixel adjoining the illustrated pixel PX on its left-hand side. Thesource line S2 is arranged at the right-hand side end in the pixel PX.Precisely, the source line S2 is arranged striding over a boundarybetween the illustrated pixel and a pixel adjoining the illustratedpixel PX on its right-hand side. Moreover, in the pixel PX, theauxiliary capacitance line C1 is arranged at the upper end portion, andthe gate line G1 is arranged approximately in the central portion of thepixel PX.

The pixel electrode PE is arranged between the source line S1 and thesource line S2. The pixel electrode PE is electrically connected withthe switching element which is not shown. The pixel electrode PE has themain pixel electrode PA in the shape of a belt extending linearly alongthe second direction Y, the sub-pixel electrode PB in the shape of abelt extending linearly along the first direction X, and the capacitanceportion PC in the shape of a belt extending linearly along the firstdirection X. The main pixel electrodes PA, the sub-pixel electrode PB,and the capacitance portion PC are electrically connected each other. Inthe illustrated example, the main pixel electrode PA, the sub-pixelelectrode PB, and the capacitance portion PC are integrally orcontinuously formed. That is, the main pixel electrode PA, the sub-pixelelectrode PB, and the capacitance portion PC are formed on the secondinterlayer insulating film 13 using the same process and the samematerial.

The main pixel electrode PA is arranged in an inside position of thepixel PX rather than the position on the adjoining source line S1 andthe source line S2, and is arranged between the source line S1 and thesource line S2. More specifically, the main pixel electrode PA isarranged in the approximately center position between the source line S1and the source line S2. The main pixel electrode PA extends fromvicinity of the upper end to vicinity of a bottom end of the pixel PX.

The sub-pixel electrode PB faces the gate line G1. The first interlayerinsulating film 12 and the second interlayer insulating film 13 areinterposed between the sub-pixel electrode PB and the gate line G1 asinsulating films. That is, the sub-pixel electrode PB is located insidethe pixel PX rather than the position on the adjoining auxiliarycapacitance line C1 and the auxiliary capacitance line C2, and isarranged between the auxiliary capacitance line C1 and the auxiliarycapacitance line C2. The sub-pixel electrode PB is arrangedapproximately in the central portion of the pixel, and morespecifically, is arranged approximately in the central portion betweenthe auxiliary capacitance line C1 and the auxiliary capacitance line C2.The sub-pixel electrode PB intersects the main pixel electrode PA, andlinearly extends toward the source line S1 and the source line S2 on theboth sides, i.e., on the left-hand side of the main pixel electrode PA,and on the right-hand side of the main pixel electrode PA, respectivelyfrom the main pixel electrode PA.

In case the sub-pixel electrode PB covers the gate line G1 in each pixelPX, that is, the sub-pixel electrode PB is arranged on the gate line G1,the width of the sub-pixel electrode PB is substantially equal to orlarger than that of the gate line G1 in the second direction Y.

The capacitance portion PC is arranged on the auxiliary capacitance lineC1. The first interlayer insulating film 12 and the second interlayerinsulating film 13 are interposed between the capacitance portion PC andthe auxiliary capacitance line C1 as insulating films. Morespecifically, the capacitance portion PC is arranged at the upper endportion of the pixel PX. The capacitance portion PC is connected withone end of the main pixel electrode PA, and linearly extends toward thesource line S1 and the source line S2 of the both sides, i.e., theleft-hand side of the main pixel electrode PA, and on the right-handside of the main pixel electrode PA, respectively from the main pixelelectrode PA.

In this embodiment, the second main common electrode CA2 is arranged atthe both sides which sandwich the main pixel electrode PA. That is, themain pixel electrode PA and the second main common electrode CA2 arearranged by turns along the first direction X. The main pixel electrodePA and the second main common electrode CA2 are arranged approximatelyin parallel. At this time, neither of the second main common electrodesCA2 overlaps with the main pixel electrode PA in the X-Y plane.

That is, one main pixel electrode PA is located between adjoining thesecond main common electrode CAL2 and the second main common electrodeCAR2. That is, the second main common electrode CAL2 and the second maincommon electrode CAR2 are arranged on the both sides which sandwich aposition above the main pixel electrode PA. For this reason, the secondmain common electrode CAL2, the main pixel electrode PA, and the secondmain common electrode CAR2 are arranged along the first direction X inthis order. The distance between the second main common electrode CAL2and the main pixel electrode PA in the first direction X issubstantially equal to that between the second main common electrodeCAR2 and the main pixel electrode PA.

According to the third embodiment, the same effect as the firstembodiment is achieved. It is possible to suppress the application ofundesirable bias from the gate line to the liquid crystal layer LQ byshielding undesirable electric field from the gate line because thesub-pixel electrode PB of the pixel electrode PE is arranged facing thegate line. Accordingly, it becomes possible to suppress the applicationof the undesired bias from the gate line to the liquid crystal layer LQ.A defect display such as a printed picture and a light leak due to analignment disorder of the liquid crystal molecule is suppressed.Accordingly, a higher quality liquid crystal display device can beoffered.

The shield performance against the electric field from the gate line isimproved with the increase of the width of the sub-common electrode PB.However, if the width of the sub-pixel electrode PB is too wide, thearea of the aperture becomes small and reduction of transmissivity iscaused. Therefore, it becomes possible to raise the electric fieldshield performance against the electric field from the gate lines G1while maintaining high transmissivity in the case where the sub-pixelelectrode PB is arranged on the gate line G1 and has substantially thesame width as the gate line G1.

Moreover, no common electrode which needs an electric insulation fromthe pixel electrode is arranged in the array substrate AR. For thisreason, it becomes possible to improve the flexibility of the layout ofthe pixel electrode PE according to the various purposes, such asformation of the retention capacitance, and shielding of the electricfield from the gate line.

In addition, the auxiliary capacitance lines are arranged at the upperend portion and the lower end portion, and the gate is arranged in thecentral portion of the pixel PX in the third embodiment. This embodimentis especially suitable for a capacitance coupling driving (CC driving).That is, the pixel voltage is reached to a predetermined voltage bysuperimposing an auxiliary capacitance signal on the pixel electrode PEthrough a retention capacitance Cs of each pixel. Thereby, signalvoltage amplitude can be approximately reduced by half if the retentioncapacitance Cs and the pixel capacitance are set to be equal. The driverIC chip 2 equipped with the gate driver GD, the source driver SD, andthe controller functions as driving means for performing the CC driving,and is equipped in the array substrate AR.

According to the embodiment using the CC driving, while being able toreduce power consumption, it becomes possible to control degradation ofdisplay grace.

Next, the effect according to this embodiment is verified.

The liquid crystal display panels LPN respectively corresponding to thefirst embodiment shown in FIG. 4 to FIG. 8, and the third embodimentshown in FIG. 10 were prepared, and the transmissivity per one pixel wasmeasured. In addition, in the first embodiment and the third embodiment,the electrode width, the distance between the electrodes, the pixelpitch, the cell gap, the liquid crystal material, the alignment filmmaterial, the alignment direction, etc., were altogether made into thesame conditions except that the forms of the pixel electrode PE and thecommon electrode CE differ each other. When the transmissivity of theliquid crystal display panel corresponding to the third embodiment wasset to 1.0, the transmissivity of the liquid crystal display panelaccording to the first embodiment was 1.1.

As explained-above, according to the embodiments, it becomes possible tooffer the high quality liquid crystal display device.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions.

What is claimed is:
 1. A liquid crystal display device, comprising: afirst substrate including; a first gate line and a second gate linerespectively extending in a first direction, a main pixel electrodearranged between the first gate line and the second gate line andextending in a second direction orthogonally crossing the firstdirection, and a pair of sub-common electrodes respectively facing thefirst gate line and the second gate line through an insulating layer andextending in the first direction, a second substrate including a pair ofmain common electrodes electrically connected with the sub-commonelectrodes and arranged on both sides sandwiching the main pixelelectrode; and a liquid crystal layer containing liquid crystalmolecules and held between the first substrate and the second substrate.2. The liquid crystal display device according to claim 1, wherein eachof the pair of the sub-common electrodes is arranged on the first andsecond gate lines having substantially the same width as those of thefirst and second gate lines.
 3. The liquid crystal display deviceaccording to claim 1, wherein the main pixel electrode is formed on theinsulating layer and formed of the same material as that of therespective sub-common electrodes.
 4. The liquid crystal display deviceaccording to claim 1, wherein an initial alignment direction of theliquid crystal molecules is a direction substantially in parallel withthe second direction.
 5. The liquid crystal display device according toclaim 1, wherein the liquid crystal display device is driven by acapacitance coupled dot inversion driving (CCDI).
 6. A liquid crystaldisplay device having a plurality of pixels, comprising: a firstsubstrate including; a first gate line and a second gate linerespectively extending in a first direction, an auxiliary capacitanceline arranged between the first gate line and the second gate line andextending in the first direction, a first insulating layer covering thefirst gate line, the second gate line, and the auxiliary capacitanceline, a first source line and a second source line extending in a seconddirection orthogonally crossing the first direction on the firstinsulating layer, a second insulating layer covering the first andsecond source lines, a main pixel electrode arranged on the secondinsulating layer and extending in the second direction, the main pixelelectrode being arranged between the first gate line and the second gateline, and between the first source line and the second source line, apair of sub-common electrodes respectively facing the first gate lineand the second gate line through the second insulating layer andextending in the first direction, and a first main common electrodefacing the first and second source lines through the second insulatinglayer and extending in the second direction, the first main commonelectrode being cut on the auxiliary capacitance line and electricallyconnected with the sub-common electrodes, a second substrate including apair of second main common electrodes electrically connected with thesub-common electrodes and the first main common electrode, and arrangedboth sides sandwiching the main pixel electrode, the second main commonelectrodes extending in the second direction; and a liquid crystal layercontaining liquid crystal molecules and held between the first substrateand the second substrate.
 7. The liquid crystal display device accordingto claim 6, wherein the first substrate further includes a capacitanceportion facing the auxiliary capacitance line through the secondinsulating layer and extending in the first direction, the capacitanceportion being apart from the first main common electrode andelectrically connected with the main pixel electrode.
 8. The liquidcrystal display device according to claim 6, wherein the capacitanceportion is located approximately in the center portion of the pixel. 9.The liquid crystal display device according to claim 6, wherein therespective sub-common electrodes are arranged on the first gate line andthe second gate line and have substantially the same widths as those ofthe first and second gate lines, and the first main common electrode isarranged on the first and second source lines and has substantially thesame width as those of the first and second source lines.
 10. The liquidcrystal display device according to claim 6, wherein the main pixelelectrode is formed of the same materials as those of the sub-commonelectrode and the first main common electrode.
 11. The liquid crystaldisplay device according to claim 6, wherein the respective second maincommon electrodes face the first main common electrode and extend in thesecond direction without being cut on the auxiliary capacitance line.12. The liquid crystal display device according to claim 6, wherein aninitial alignment direction of the liquid crystal molecules is adirection substantially in parallel with the second direction.
 13. Theliquid crystal display device according to claim 6, wherein the liquidcrystal display device is driven by a capacitance coupled dot inversiondriving (CCDI).
 14. A liquid crystal display device having a pluralityof pixels, comprising: a first substrate including; a first auxiliarycapacitance line and a second auxiliary capacitance line respectivelyextending in a first direction, a gate line arranged between the firstauxiliary capacitance line and the second auxiliary capacitance linerespectively extending in the first direction, a main pixel electrodeextending in a second direction orthogonally crossing the firstdirection, a sub-pixel electrode facing the gate line through aninsulating layer and extending in the first direction, the sub-pixelelectrode being electrically connected with the main pixel electrode, asecond substrate including a pair of main common electrodes arranged onboth sides sandwiching the main pixel electrode and extending in thesecond direction; and a liquid crystal layer containing liquid crystalmolecules and held between the first substrate and the second substrate.15. The liquid crystal display device according to claim 14, wherein thesub-pixel electrode is arranged on the gate line and has a substantiallythe same width as that of the gate line.
 16. The liquid crystal displaydevice according to claim 14, wherein the main pixel electrode is formedon the insulating layer using the same material as that of the sub-pixelelectrode.
 17. The liquid crystal display device according to claim 14,wherein an initial alignment direction of the liquid crystal moleculesis a direction substantially in parallel with the second direction. 18.The liquid crystal display device according to claim 14, wherein themain pixel electrode includes a capacitance portion arranged facing oneof the auxiliary capacitance lines to form a retention capacitance. 19.The liquid crystal display device according to claim 14, wherein thegate line is arranged approximately in the center portion of the pixel.20. The liquid crystal display device according to claim 14, wherein theliquid crystal display device is driven by a capacitance couplingdriving (CC driving).